Production of 1,6-and 1,7-octadienes

ABSTRACT

1,6- AND/OR 1,7-OCTADIENES ARE PRODUCED BY REACTING A 1,3-BUTADIENE SUCH AS BUTADIENE ITSELF WITH METALLIC PLATINUM, PALLADIUM, RHODIUM, RUTHENIUM OR OSMIUM OR PREFERABLY WITH A COMPOUND OF ONE OR MORE OF THESE METALS IN A NON-POLAR SOLVENT SUCH AS BENZENE IN THE PRESENCE OF A REDUCING AGENT SUCH AS FORMIC ACID.

United States Patent Office Patented July 9, 1974 3,823,199 PRODUCTION OF 1,6- AND 1,7-OCTADIE NES Donald Wright, Stockton-on-Tees, England, asslgnor to Imperial Chemical Industries Limited, London, England No Drawing. Filed Aug. 7, 1972, Ser. No. 278,343 Claims priority, application Great Britain, Aug. 18, 1971, 38,734/71 Int. Cl. C07c 11/12 US. Cl. 260-680 B 7 Claims ABSTRACT OF THE DISCLOSURE 1,6- and/or 1,7-octadienes are produced by reacting a 1,3-butadiene such as butadiene itself with metallic platinum, palladium, rhodium, ruthenium or osmium or preferably with a compound of one or more of these metals in a non-polar solvent such as benzene in the presence of a reducing agent such as formic acid.

The present invention relates to the production of olefines.

In our co-pending Application No. 79,323, now US. Pat. 3,732,328, we have described and claimed a process for the production of 1,6- and/or 1,7-octadienes by contacting one or more acyclic conjugated di-olefines with metallic platinum, palladium, rhodium, ruthenium or osmium or with a compound of one or more of these metals in a polar solvent in the presence of a reducing agent.

We have now found that the process may also be carried out in a non-polar solvent such as benzene.

According to the present invention 1,6- and/ or 1,7-octadienes are produced by contacting one or more acyclic conjugated di-olefines with metallic platinum, palladium, rhodium, ruthenium or osmium or with a compound of one or more of these metals in a non-polar solvent in the presence of a reducing agent.

The acyclic conjugated diolefine contains the structure:

in which the residual valencies may be satisfied by organic or inorganic groups or by hydrogen. Preferably the residual valencies are satisfied by alkyl groups, particularly lower alkyl groups containing up to four carbon atoms, or by hydrogen. The most suitable acyclic conjugated diolefines for use in the process of the invention are those in which the residual valencies are satisfied by methyl groups and/or by hydrogen. Butadiene and isoprene are particularly preferred. Halogen atoms such as chlorine are examples of suitable inorganic substituents in the acyclic conjugated diolefine. If desired two or more diolefines may be used in admixture.

The products of the process are substantially acyclic dimers of the acyclic conjugated diolefines and comprise an octadiene chain in which unsaturation is present in the 1,6- or 1,7-position. Thus platinum or a platinum compound and palladium or a palladium compound tend to produce a product comprising substantially the 1,6- isomer without any of the 1,7-isomer. If the palladium or platinum catalysed reaction is carried out in the presence of a phosphine, however, the 1,7-isomer is also formed, the relative proportions of the two isomers obtained being influenced by the nature of the phosphine. If the phosphine used is a triaryl phosphine then formation of the 1,6-octadiene is favoured whereas in the presence of a trialkyl phosphine the 1,7-isomer tends to be produced. Suitable triaryl phosphines include triphenyl phosphine; tri (alkyl phenyl) phosphines, particularly those in which each alkyl group contains up to 6 carbon atoms such as tri(p-tolyl phosphine); and tri(substituted phenyl) phosphines in which the substituent is non-hydrocarbon, e.g.

tri(p-methoxy phenyl)-phosphine. Trialkyl phosphines which may be used include alkyl phosphines in which each alkyl group contains up to 6 carbon atoms, e.g. triethyl and tributyl phosphine and trialkyl phosphines in which the alkyl group contains other substituents, e.g. a phenyl group as in tribenzyl phosphine. Tricycloalkyl phosphines may also be used, influencing the reaction in the same way as the trialkyl phosphines. The concentration of the phosphine preferably lies in the range 10" to 10* molar.

The reaction may be carried out heterogeneously using the metal or a metal compound. In the heterogeneous reaction the metal or metal compound may be supported on an inert support such as silica, alumina, charcoal or pumice. Preferably, however, the reaction is carried out homogeneously in the liquid phase. Suitable noble metal compounds which may be used in both the homogeneous and heterogeneous reactions include metal halides, particularly the chlorides, e.g. platinous chloride, rhodium trichloride and palladous chloride; metal carboxylates, particularly metal alkanoates derived from alkanoic acids containing up to six carbon atoms such as platinous acetate and palladium acetate, and complexes of the metals such as platinum or palladium acetylacetonate, bis-benzonitrile palladium (II) and lithium palladous chloride. The concentration of the metal or metal compound is preferably catalytic, e.g. in the range 10 to 10- molar, preferably 10 to 10 molar.

The non-polar solvent may be a hydrocarbon such as a paraffin, cycloparafiin or an aromatic. Preferably the solvent is a parifiin containing 5 to 16 carbon atoms, e.g. hexane, dodecane, or pentadecane, or is benzene, or an alkyl benzene, particularly an alkyl benzene containing up to 12 carbon atoms such as toluene or a xylene, or is a cycloparaflin, e.g. cyclohexane or methyl cyclohexane.

The reducing agent is preferably a liquid reducing agent. Examples of such agents include hydrazine and formaldehyde and solutions containing an alcohol, particularly a lower alkanol such as isopropanol. A preferred reducing agent is formic acid. The concentration of the reducing agent is preferably in the range 0.5 to 10 molar. A gaseous reducing agent such as hydrogen may also be used.

The process may be carried out at a temperature in the range 20 to 200 C. When operating at the higher temperatures the reaction may take place in a sealed system under the autogeneous pressure of the reactants.

If the process is carried out in a steel reaction vessel then it is advantageous to provide a copper salt, e.g. copper sulphate, or a copper halide such as copper chloride or a copper alkanoate such as copper acetate, or a phosphine such as a trialkyl, a mixed alkylaryl or a triaryl phosphine, e.g. triphenyl phosphine in the reaction mediuml tfo improve the activity of the catalyst and to prolong its 1 e.

The product of the process is either a 1,6 or 1,7 octadiene or a mixture of the two. The terminal unsaturation in the 1,7-diolefine makes it particularly useful as a chemical intermediate while the 1,6-isomer finds use as a termonomer with ethylene and propylene in EP rubbers.

The invention will now be further described with reference to the following Examples.

EXAMPLE 1 A mixture of formic acid (12 grams, 0.26 mole), benzene (20 mls.), palladous acetate (22 m. grams, 0.0001 mole) and butadiene (50 mls. 0.63 mole) Was heated in an autoclave at 50 C. for 20 hours. At the end of this time the excess formic acid was removed by washing with water and the organic phase dried and distilled to give 3.0 grams of 1,6-octadiene boiling at 46 C./50 mm.

EXAMPLE 2 A mixture of formic acid (12 grams, 0.26 mole), benzene (20 mls.), platinum acetylacetonate (9.3 m. grams, 0.000024 mole) and butadiene (50 mls.) was heated in an autoclave at 80 C. for 10 hours. The excess formic acid was removed from the product by washing with water subsequent distillation of the organic phase yielding 8 grams of 1,6-octadiene boiling at 66 C./ 130 mm.

What I claim is:

1. A process for the production of a member of the group consisting of 1,6- and 1,7-octadienes which comprises contacting at least one acyclic conjugated diolefine selected from the group consisting of butadiene and isoprene with a member of the group consisting of metallic platinum, palladium, rhodium, ruthenium, osmium and compounds of at least one of these metals in a non-polar solvent in the presence of formic acid.

2. The process of Claim 1 in which the process is carried out homogeneously in the liquid phase.

3. The process of Claim 2 in which the metal compound is a halide or a carboxylate or is a complex of one of said metals.

4. The process of Claim 2 in which the solvent is a parafiin, a cycloparaffin or an aromatic hydrocarbon.

5. The process of Claim 2 when carried out in a steel reaction vessel in which a copper salt is present.

6. The process of Claim 2 in which a phosphine is present.

7. The process of Claim 2 in which isoprene or butadiene is contacted at a temperature of 20 to 200 C. with, (a) a 10* to 10' molar concentration of a metal compound selected from the group consisting of palladous chloride, platinous chloride, a palladous alkanoate containing up to 6 carbon atoms, a platinous alkanoate containing up to 6 carbon atoms, platinum acetylacetonate, palladium acetylacetonate, bis-benzonitrile palladium (II) and lithium palladous chloride,

(b) in a non-polar solvent selected from the group consisting of a paraflin containing 5 to 16 carbon atoms, benzene, toluene, xylene, cyclohexane and methylcyclohexane,

(c) in the presence of formic acid in a concentration of 0.5 to 10 molar.

References Cited UNITED STATES PATENTS 3,398,209 8/1968 Schneider et al. 260-680 B 3,478,123 11/1969 Brennan 260-677 R 3,510,536 5/ 1970 Brennan 260-680 B 3,732,328 5/1973 Wright 260-680 B 3,354,236 11/1967 Klein 260-683.15 B 3,534,088 10/1970 Bryant et al. 260-666 B PAUL M. COUGHLAN, JR., Primary Examiner 

